Deallocation in cv::Mat of externally allocated memory (Bug #2799)

Added by Evgeny Elkin about 12 years ago. Updated over 11 years ago.

Status:Cancelled Start date:
Priority:Normal Due date:
Assignee:Vadim Pisarevsky % Done:

0%
Category:core
Target version:-
Affected version:2.4.0 - 2.4.4 Operating System:
Difficulty: HW Platform:
Pull request:

Description

Behaviour is changed since previous version.

Is it correct, that opencv could delete memory pointer, allocated somewhere outside the library?

I have noticed that when I use this c-tor:

cv::Mat(int ndims, const int* sizes, int type, void* data, const size_t* steps=0)

In stock 2.4.3, where data is pointer to some memory allocated before. Then, when cv::Mat will be destroyed, data will be deallocated (in my case only try to deallocate)

void Mat::deallocate()
{
    if( allocator )
        allocator->deallocate(refcount, datastart, data);
    else
    {
        CV_DbgAssert(refcount != 0);
        fastFree(datastart);
    }
}

I think in this case (allocator==0, OpenCV does not own the memory) fastFree call is incorrect.

Associated revisions

Revision 41ceadf9
Added by Vadim Pisarevsky over 10 years ago

Merge pull request #2799 from 23pointsNorth:patch-1

History

#1
Updated by Kirill Kornyakov about 12 years ago

Good question, but please format your description properly next time (use pre tag and proper case).

Vadim, what are your thoughts?

  • Category set to core
  • Assignee set to Vadim Pisarevsky
  • Subject changed from Deallocation in cv::Mat of non opencv data to Deallocation in cv::Mat of externally allocated memory
  • Description changed from Behaviour is changed since previous version. Is it correct, that opencv coul... to Behaviour is changed since previous version. Is it correct, that opencv coul... More

#2
Updated by Michael Lou almost 12 years ago

Happened to find this bug report. In my opinion, this should not be a problem.
In the case when matrix points to user-allocated data, the refcount pointer is NULL.
Therefore, the destructor would not call deallocate() function.

Mat::~Mat()
{
    release();
    if( step.p != step.buf )
        fastFree(step.p);
}


void Mat::release()
{
    if( refcount && CV_XADD(refcount, -1) == 1 )
        deallocate();
    data = datastart = dataend = datalimit = 0;
    size.p[0] = 0;
    refcount = 0;
}

Evgeny Elkin wrote:

Behaviour is changed since previous version.

Is it correct, that opencv could delete memory pointer, allocated somewhere outside the library?

I have noticed that when I use this c-tor:

[...]

In stock 2.4.3, where data is pointer to some memory allocated before. Then, when cv::Mat will be destroyed, data will be deallocated (in my case only try to deallocate)

[...]

I think in this case (allocator==0, OpenCV does not own the memory) fastFree call is incorrect.

#3
Updated by Andrey Pavlenko over 11 years ago

  • Status changed from Open to Cancelled
  • Affected version changed from 2.4.3 to 2.4.0 - 2.4.4
  • Start date deleted (2013-02-14)

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